Our previous work revealed that psychomotor stimulant drugs such as MDMA and methamphetamine induce robust changes in brain temperature. These hyperthermic effects are strongly potentiated by social interaction and warm environment--two conditions often associated with human drug use. In this year, we worked with morphine and oxycodone--two widely used analesic opioid drugs that are widely abused and could result in lethality during overdose. We also continued our work with fentanyl and showed that even small contamination of heroin with fentanyl results in dramatic potentiation of its temperature effects. By using multi-site temperature recordings, we clarified the role of metabolic brain activation and skin vascular response in mediating temperature effects of morphine and oxycodone in wide range of doses.